Resin-impregnated sheet and resin-impregnated sheet with conductive layer

Abstract

A resin-impregnated sheet is provided in which a dielectric loss tangent is small. In a preferred embodiment the sheet is prepared by impregnating a fiber sheet with a liquid crystal polyester which has a repeating unit represented by formula (1), a repeating unit represented by formula (2), and a repeating unit represented by formula (3), in which a content of a repeating unit comprising a 2,6-naphthylene group is 40 mole % or more based on a total amount of all repeating units, as follows: (1)-O—Ar 1 —CO—; (2)-CO—Ar 2 —CO—; and (3)-O—Ar 3 —O— wherein Ar 1 represents a 2,6-naphthylene group, a 1,4-phenylene group, or a 4,4′-biphenylylene group; Ar 2 and Ar 3 each independently represent a 2,6-naphthylene group, a 1,4-phenylene group, a 1,3-phenylene group, or a 4,4′-biphenylylene group; and hydrogen atoms present in the group represented by Ar 1 , Ar 2 , or Ar 3 may each independently be replaced by a halogen atom, an alkyl group, or an aryl group.

1 . A resin-impregnated sheet prepared by a fiber sheet being impregnated with a liquid crystal polyester which has a repeating unit represented by formula (1), a repeating unit represented by formula (2), and a repeating unit represented by formula (3) and in which a content of a repeating unit comprising a 2,6-naphthylene group is 40 mole % or more with respect to a total of all repeating units,
   —O—Ar 1 —CO—  (1)
     —CO—Ar 2 —CO—  (2)
     —O—Ar 3 —O—  (3)
   wherein Ar 1  represents a 2,6-naphthylene group, a 1,4-phenylene group, or a 4,4′-biphenylylene group; Ar 2  and Ar 3  each independently represent a 2,6-naphthylene group, a 1,4-phenylene group, a 1,3-phenylene group, or a 4,4′-biphenylylene group; and hydrogen atoms present in the group represented by Ar 1 , Ar 2 , or Ar 3  may each independently be replaced by a halogen atom, an alkyl group, or an aryl group.   
     
     
         2 . The resin-impregnated sheet according to  claim 1 , prepared by the fiber sheet being melt impregnated with the liquid crystal polyester. 
     
     
         3 . The resin-impregnated sheet according to  claim 1 , prepared by a sheet composed of the liquid crystal polyester and the fiber sheet being pressed. 
     
     
         4 . The resin-impregnated sheet according to  claim 1 , wherein a fiber constituting the fiber sheet is a glass fiber. 
     
     
         5 . A resin-impregnated sheet with a conductive layer, comprising the resin-impregnated sheet according to  claim 1 , and a conductive layer formed on at least one surface of the resin-impregnated sheet.